(1) Field of the Invention
The invention relates to lenses for viewing devices, such as periscopes, telescopes and microscopes, and is directed more particularly to a lens frame and a pocket for receiving same for use on a submarine periscope.
(2) Description of the Prior Art
In current submarine periscopes, circular lenses are screwed into place when needed. The lenses are affixed to a periscope assembly eye guard housing and, in particular to a component thereof referred to as a xe2x80x9cblinder assemblyxe2x80x9d. The blinder assembly serves to block out light to one eye of an operator and permit light to pass through a viewing aperture having therein a lens, such as a clear glass or, alternatively, a filter, to the other eye of the operator. When a lens is not in use, it often becomes misplaced or lost. There is no storage facility for lenses on the blinder assembly and, being relatively small (about 1 inch in diameter), the lenses are easily set aside and forgotten until needed, by which time the lens has frequently disappeared. However, even when properly stored and retrieved, screwing the lens into a blinder assembly requires a steady hand, sometimes under pressure.
In U.S. Pat. No. 2,953,970, issued Sep. 27, 1960, to Charles A. Maynard, there is shown a lens assembly in which one or more lenses are attached in telescopic fashion to an optical apparatus. A first lens is provided with a magnetic ring which is magnetically attracted to a magnetically permeable barrel ring of the optical apparatus. By virtue thereof, the first lens is held on the optical apparatus. A second lens may similarly be mounted on the first lens, and so on with additional lenses, to provide a series of axially aligned lenses selected for a given purpose.
In Maynard, adjacent lens retaining rings contain permanently magnetic portions, the poles of which are alignable with unlike poles in an adjacent ring. Each ring is provided with both north and south poles directed in each of two axial directions. The various unlike poles are attracted to each other to support one ring with respect to an adjacent ring. To disengage one ring from another, one ring is rotated with respect to the adjacent ring until similar poles are aligned, to cause a repelling force between the adjacent rings, which aids in disassembly. Alternatively, one ring may be rotated to a point of equilibrium, or non-attraction between the rings, permitting one ring to be detached from the adjacent ring.
The handling of the lens rings in the Maynard apparatus is thus not far removed from the current screw thread attachment in submarine periscope assemblies, described briefly above. Having to rotatably align rings so as to achieve magnetic equilibrium or repelling forces, is still required under less than ideal conditions.
Accordingly, there is a need for a lens which easily can be stored, retrieved from storage, and inserted into and removed from a pocket or housing in the periscope blinder assembly, and all done in a time efficient manner.
An object of the invention is, therefore, to provide a lens assembly and housing therefor for use in conjunction with a submarine periscope, and which is easily and quickly stored, and easily and quickly retrieved from storage for use. The lens is slipped into place in a pocket or housing in the blinder assembly and held in place without the use of tools or discrete fasteners, but easily removed from the blinder assembly and returned to storage.
With the above and other objects in view, as will hereinafter appear, a feature of the invention is the provision of a lens assembly and lens assembly housing for use in conjunction with an optical apparatus. The lens assembly comprises a generally planar lens frame of nonferrous material and defining a window having a lip therein disposed along a periphery of the window, a lens disposed in the window and adjacent the lip, a pair of spaced magnets on the frame, and a grip formed on the frame. The lens assembly housing comprises first and second walls opposed to each other and in part defining a pocket, the first wall being nonferrous and the second wall being magnetically permeable, the pocket being adapted to receive the lens assembly with the grip of the frame extending beyond the pocket. The magnets interact with the magnetically permeable second wall of the pocket to releasably retain the lens assembly in the lens assembly housing.
The above and other features of the invention, including various novel details of construction and combinations of parts, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular device embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.